Australopithecus afarensis

So far Australopithecus afarensis fossils have only been found in Eastern Africa; more specifically Hagar, Ethiopia and Laetoli, Tanzania. The fossils of A. afarensis are the oldest well-established species in the hominid line. They date from four to three million years ago.

A. afarensis was an important find because it verified that bipedalism was present before a significant increase in brain size was. There is a great deal of evidence to support the idea that A. afarensis was a bipedal species: the foramen magnum was located at the bottom of the skull, rather than at the back of it; the angle that the femur bone slanted in at was consistent with the angle required for bipedalism; and the pelvis is flared, which indicates that it could support the organs when the species stood upright.

A. afarensis had canines that extended slightly below the chewing surface. Therefore the species also had a small diastema, which is a space on the jaw allowing the canines to slash passed each other and the jaw to close. In addition, A. afarensis had wide incisors. It also had a great deal of bone inside the jaw to support heavy chewing. The zygomatic arch, cheek bone, was significantly large, allowing room for thick chewing muscles.

Neither a chin nor a forehead were present in A. afarensis. The species had a large bone over the brow, the superorbital torus, which narrowed the chance that a forehead would be present. The fossils of A. afarensis also indicate that its lower face projected outwards.

So far the most famous example of A. afarensis is Don Johanson's Lucy. Lucy was also the first specimen of A. Afarensis found.